1. Field of the Invention
This invention relates to a reversible ratchet mechanism for ratchet tools.
2. Description of the Related Art
With reference to FIG. 1 as a 3D exploded view, a conventional ratchet screwdriver mainly comprises a positioning mount 10 provided with a joint terminal 11 and a positioning terminal 12 the front side of which is formed with an open slot 13 around which two symmetrical U grooves 14a and 14b are formed into which wedge tablets 15a and 15b are each wedged; a U-shaped elastic flake 16 provided in the open slot 13 two free ends of which respectively lean against elastically the opposite inner sides of wedge tablets 15a and 15b; a reversible ring 20 set around the positioning terminal 12 the inner circumference of which is concave and formed with two wedge slots 21a and 21b that may lead the wedge tablets 15a and 15b to run and reverse; and a ratchet 30 set around the positioning terminal 12 the inner side of which is formed with a gear 31 that wedges the driving portions of wedge flakes 15a and 15b. 
Refer to FIGS. 2A, 2B, 3A, and 3B that are shown as sectional views illustrating the middle section and front section of the positioning terminal of conventional ratchet screwdriver. When the reversible ring 20 stay at an initial site, the driving portions of wedge flakes 15a and 15b are positioned in the wedges slots 21a and 21b; further, the U-shaped elastic flake elastically leans against the gear 31 of ratchet 30 and thus the ratchet 30 cannot clutch. When the reversible ring 20 counterclockwise runs at an angle, the wedge slot 21b leads the wedge flake 15b to counterclockwise run by means of a leading inclined plane 23 and be blocked on an inner torus 24 of the reversible ring 20. Thus, the driving portion of wedge flake 15b releases from the gear 31 of ratchet 30 to make the ratchet 30 clockwise clutch.
With reference to FIGS. 4A and 4B illustrating manners of reversing the conventional ratchet tool, the leading inclined planes 23 of wedge slots 21a and 21b rub the driving portions of wedge flakes 15a and 15b. Working for a long time, the leading inclined plane 23 is worn and damaged. In the embodiment, when the leading inclined plane 23 of wedge slot 21b, although the reversible ring 20 lead the wedge flake 15b to counterclockwise run, the driving portion is kept off the worn leading inclined plane 25 and thus interferes with and releases from the gear 31 of the ratchet 30.
Consequently, because of the technical defects of described above, the applicant keeps on carving unflaggingly through wholehearted experience and research to develop the present invention, which can effectively improve the defects described above.